Trim and spiralize the zucchini (see notes below for how to do this without a spiralizer). Cut extra long noodles so that they are about the length of spaghetti.
Add olive oil, garlic, and the red pepper flakes to a large, deep skillet. Turn to medium heat. When the oil begins to bubble around the garlic, add the zucchini noodles. Toss the noodles with pasta tongs and cook until al dente — they should be wilted, but still have a crunch; 5 to 7 minutes. Do not let the noodles cook any longer or else they will become mushy. As they cook, keep tossing so that all the zucchini noodles have a chance to hit the bottom of the skillet.
Stir in the tomatoes, basil, and parmesan cheese. Cook for one minute. Use pasta tongs to transfer the noodles, tomatoes, and basil to a serving dish. Leave the liquid in the skillet.
Bring the liquid left in the skillet to a simmer.
Combine cornstarch and cold water in a small bowl then whisk into the simmering liquid. Cook, while whisking until the liquid thickens to a sauce; about 1 minute.
Taste the sauce and season with salt. Pour the sauce over the zucchini, tomatoes, and basil. Finish with more parmesan cheese on top and serve immediately.
Adam and Joanne's Tips
How to make Zucchini Noodles without a Spiralizer: The spiralizer is not the only way to make noodles. You can use a julienne vegetable peeler or a mandoline. You can also use a standard vegetable peeler to make wide noodles or ribbons.
Don’t be surprised if after the pasta has been sitting, liquid collects at the bottom of the serving dish. This is okay with us. The liquid mixes with tomato, garlic, cheese, and olive oil, so it’s delicious.
Parmesan cheese may not be vegetarian since it can be made with rennet. Swap for any vegetarian-friendly hard cheese or use nutritional yeast. When using nutritional yeast, add to your tastes. I’d start with 2 tablespoons and increase from there.
4 medium zucchini (about 2 pounds)
3 tablespoons extra virgin olive oil
1 tablespoon minced garlic (3 to 4 cloves)
1/4 to 1/2 teaspoon crushed red pepper flakes, depending on how spicy you like the pasta
2 medium tomatoes, chopped, see note (about 12 ounces)
1/2 cup shredded parmesan cheese, plus more for serving, see notes for alternatives
1 cup basil leaves, torn into pieces
1 teaspoon cornstarch
2 teaspoons cold water
Salt, to taste